Abstract:
This was a joint project between scientists and scientific programmes of the US, UK, Germany, and New Zealand to collect geophysical and site survey data in support of the ANDRILL Program. Surveys were conducted over two successive Antarctic field seasons.

In the first season, the program acquired 40 km of seismic reflection data in the New Harbour area and on ... the Ross/McMurdo ice shelf between Hut Point Peninsula and Ross Island. Three 80 km line grids (New Harbour, Windless Bight/McMurdo Ice Shelf, Southern McMurdo Ice Shelf) were traversed with a magnetometer and gradiometer for gravity and magnetic measurements. An area of 5000 km2 was covered by a helicopter-borne aeromagnetic survey between Hut Point Peninsula, White Island and Minna Bluff/Brown Peninsula. Immediate scientific goals were to identify sedimentary basins beneath New Harbour and the McMurdo and Southern McMurdo Ice Shelves, determine sediment thickness and the nature of bounding faults. Beneath New Harbour, a series of 200-500 m deep/thick channels and channel fill sediments are identified that relate to the Taylor and Ferrar paleovalleys. The Taylor sequence appears to pre-date and be overprinted by the Ferrar sequence. The channel sediments overlie an older east/north east dipping set of strata cored by CIROS-1. The stratal sets are bounded west and east by major north-south trending faults related to the Transantarctic Mountain front, however, making it difficult to correlate directly to the nearby CIROS and MSSTS drillholes.

In the second season, 40 km of seismic reflection and gravity data was collected from the McMurdo and southern McMurdo Ice Shelves. Immediate scientific goals were to gain new knowledge of the role of volcanism on the development of the Victoria Land Basin, and to better understand the relationship between volcanism and sedimentation in the vicinity of Ross Island and Minna Bluff. In terms of ANDRILL drill site location this new data has elucidated 2 thick sedimentary records under the McMurdo Ice Shelf: (1) A >1000 m thick sedimentary fill beneath the 900 m deep flexural moat around Ross Island between Ross and White Islands. (2) A >600 m sedimentary record under 500 m of water in the flexural moat related to Mt Discovery/Morning between Mt Discovery and Black Island. A total of four seismic lines have now been acquired in Windless Bight which elucidate sedimentray basins that have formed as a consequence of loading of the crust/seafloor by Mt Terror volcano and the Younger Erebus volcano. This new data allows us to understand the geometry and age of the drilling targets. The data will also be used in developing models of crustal flexure as a result of volcanic loading.

Aitken, A., 2003, Preliminary fieldwork report for a geophysical assessment of the lithospheric flexure associated with the load of the Ross Archipelago, Antarctica. University of Otago Masters Thesis Progress Report.